Second-site suppressor mutations of inactivating substitutions at Gly247 of the tetrcycline efflux protein, Tet(B)

Results show that tetracycline resistance, mediated by the transmembrane helix 8 of the tetracyline efflux protein Tet(B), is abolished when Gly247 is substituted with aspartate or aspergine. However, partial restoration is accomplished by second site suppressor mutations in transmembrane helix 5 or in cytoplasmic loops.